I just finnished my 89 GT from just a roller in the begining, and I have a bad vibration at 60 and up. I suspect the drive shaft, but the input shaft bearing is also makeing some noise. If you have any ideas what i should look for let me know Thanks
I agree, check the wheel balance first. I had a bad vibe over 60 too and when I did my 5 lug swap to some Bullitts that only had about 10k miles on them it got rid of about 80% of it. Swapped to an aluminum driveshaft and it's nearly gone now.
tires>drive shaft yokes>drive shaft balance/straightness. Some drive shafts have a balance weight on them that i've seen break loose, causing that vibration. Sometimes the vibration can be caused by gear installation, but my guess is that the gear just brings a problem that might have been small closer to your attention, ya know? The aluminum driveshaft solved this problem for me, and it actually ended up being the stock shaft...a friend of mine tried the shaft on another car (he had the same problem) and it still vibrated.
^^^^^^good advice by all. When I was getting a viration in my 96 @60-70 mph it ended up being the front u-joint. Other than that the u-joint never made a sound or anything just vibrated.
I had the same problem after installing the 3.73's because of the additional driveshaft speed...new u joints and a retubed and balanced driveshaft for 100 bucks fixed the problem